Casing expander



March 7, 1950 P, LARK 2,499,630

CASING EXPANDER Filed Dec. 5, 1946 Vb z Fig. 3

PAUL B. CLARK INVENTOR.

41. BIZQMJE By ATTORNEYQ;

' of the well in feet.

Patented Mar. 7, 1950 UNITED STATES PATENT OFFICE 1 The inventionrelates to a casing reaming tool ,or expander to be used in pipe in situin a well bore.

In the rotary method of drilling wells, the drill bit is rotated bymeans of a drill stem and drilling mud circulated downwardly through thebit and upwardly through the well bore. Such mud is sufflciently heavyto prevent caving of the earth formation until the well is completed,whereupon a string of pipe is lowered into the well bore and firmlyanchored into position. It is well known that the pressure of the earthformations, which are in pounds per square inch, can be expected toapproximate 0.45 of the depth Thus in a ten thousand foot well, apressure of 4500 pounds per square inch can be expected. During thecirculation of the drilling mud, it is not uncommon to loosen theportions of formation around the well bore and after the casing has beenset in position, quite often the caving of the earth formation againstthe casing causes it to collapse or to be indented due to the externalpressure. This is particularly true where the heavy drilling mud hasbeen washed out of the casing and replaced with a liquid of lesserspecific gravity. Many wells have been junked and abandoned due to thecollapse of the casing, where such collapse restricted the passagethrough the casing to such an extent that it was either impossible tocomplete the well or to continue production.

The present invention directs itself to a means and method of expandingthe casing to its original position after it has once been collapsed andwhile the casing stem remains in place in the well.

It is one of the objects of the invention to provide a tool which may belowered into a well bore and by rotation and the application of alowering force thereto operated to enlarge an area in a pipe.

Another object of the invention is to provide a method of reaming andexpanding a collapsed casing in a well bore.

A still further object of the invention is to provide a tool forexpanded collapsed casing in the well bore where the tool has taperedrolling surface thereon which can be forced against the reduced area ofthe casing.

Other and further objects of the invention will be readily apparent whenthe following description is considered in connection with theaccompanying drawings, wherein:

Fig. 1 is a vertical sectional view taken on the line |l of Fig. 2, andillustrating, the tool embodying the invention.

a Fig. 2 is a section taken on the line 2-2 of Fig. 1.

Fig. 3 is a vertical sectional view of a portion of collapsed casing inthe well with the tool in posi-' tion ready to execute the expansion orreaming of the casing.

In Fig. 3 the well bore 2 has been drilled by the rotary method and thestring of pipe 3 generally known as casing has been lowered intoposition. The earth formation 4 has caved in or in some manner exertedan excessive pressure upon the outer periphery 5 of the casing 3. Thispressure has curved the casing inwardly at 6 and I to create a reducedarea 8 where the casing has been collapsed. In some instances, thecollapsing action substantially exceeds that shown in Fig. 3 which ismerely illustrative.

In order to restore the casing to its original contour and to eliminatethe restriction in the size of the passage through the pipe, a tool Ithas been devised which includes the body ll having a threaded box [2 atits upper end to receive a string of drill pipe 13 by which the tool isoperated.

The body ll of the tool has a passage it therethrough for thecirculation of liquid if such circulation and washing action is desired.

As seen in Fig. 2 the body H has been formed with a plurality ofrecesses or pockets l6 which are segments of a cylinder and which arearranged in the periphery of the body. As seen in Fig. 1 each of thesepockets i6 is arranged to receive a roller or expander l1. Each of theseexpanders is a frusto-conical member which may have a knurled surface 58and which is arranged for rotation upon a spindle IS. The spindle i9 isarranged for insertion in a recess 20 formed in the outstanding shoulderportion 2| on the body, the body having been cut away at 22 to permitthe drilling of the bore 20. This bore extends through the shoulder 25and through the bottom surface '23 of the pockets 96 so as to form abore 28 which receives the lower end of the shaft or spindle I 9. Ashoulder 25 formed by reducing the size of the body 5 i and thethreading thereof at 26 provides an area to receive the cap or nippie2'? which is threaded thereon and tapered at 23.

In order to hold the spindle l9 against rotation, the bore 2 3 has beenextended at 30 into the upper portion of the threaded area 26 andthrough the shoulder 25. An eccentric extension 32 on the lower end ofthe spindle l9 fits rotation by the nipple or cap 21. It seems obviousthat the reamer or roller I! along with the thrust washer 35 can beslipp d into the pocket It and the spindle I! moved into the bore andthrough the roller to the position shown in Fig. 1. A retainer screw 86can then be placed in position to insure that the spindle will not workitself out of position.

Fig. 2 shows three such assemblies carriedby the body and particularattention is directed to the fact that the reaming knurled surface I8 istapered and additionally inclined due to the inclination of the spindle19 so that the three rollers when taken together form a tapered lowersurface which can be wedged into the reduced area I as seen in Fig. 3.

The pipe II will probably be a drill pipe which has a substantial weightand which is capable of applying a substantial rotative torque to thetool.

In operation the tool will be aflixed to the lower end of the pipe 13and lowered into the well bore until it reaches the collapsed portion.The pipe I! will then be rotated and at least a portion of the weight ofthe drill pipe i 3 applied thereto so as to gradually expand thecollapsed area 8 forcing the earth formation 4 back with the casing soas to restore the casing to its original cylindrical configuration.

Broadly the invention relates to a means and method of expandingcollapsed casing in place in a well bore.

What is claimed is:

A casing expander including a cylindrical body, a passage therethrough,a threaded box area on the top to connect a string of pipe thereto, athreaded pin on the lower end of said body, a pocket in the periphery ofsaid body, a reduced area on the body above said pocket to provide g 4 Ya shoulder. a bore extending into the pocket from said shoulder andinclined inwardly and downwardly, a continuation of said bore in thebottom of said et and extending into am outer recess in the top of saidpin, a shaft in said bores, a frusto-conical reaming roller on saidshaft with the larger portion thereof at the top so that said rollerpresents an inclined surface to roll on a reduced area of a casing in awell bore so that as said body is rotated and pressure applied thereto,the reduced area of the casing will be enlarged, said shaft having aneccentric portion on the lower end thereof lying within said recess, anda cap on said pin member covering said recess to retain such eccentricportion and to hold the shaft against rotation.

PAUL B. CLARK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

